The Reventazon Hydroelectric Dam is Central America's largest renewable energy project. In 2016 the 130 meter-high dam flooded the Reventazon Valley creating an 8-kilometer long artificial lake which completely dissects the Barbilla-Destierro Biological Corridor. The map below shows the geographical position of the new lake.

NEGATIVE ENVIRONMENTAL IMPACT

The dam's constructors the Instituto Costarricense de Elecricidad (ICE) were specifically bound by its financiers, the World Bank and the Inter-American Development Bank, to "restore and maintain connectivity within the Barbilla-Destierro Corridor" as a basic pre-requisite of the project's approval.

The ICE were paid $2.7 million to ensure that biological connectivity was maintained, including the reforestation of a wide buffer zone around the edge of the new lake in order to assist migration. Despite this the reforestation has still not been completed.

Instead, in direct conflict with this priority goal the ICE has erected a new and formidable barrier around the entire circumference of the lake in the form of a 5-layer barbed wire fence. Rather than helping to maintain connectivity, this fence seriously compounds the negative environmental impact of the lake and critically impedes the migration of all large mammals through the corridor.

This new fence now encompasses the Reventazon Reservoir

THE LANCASTER WETLANDS

With the creation of the Reventazon Reservoir the only viable migration route for large mammals across the Reventazon Valley is now around the "tail" of the lake at it's southern end. This area is known as the Lancaster Wetlands, which was highlighted by the Inter-American Development Bank in 2012 as being "the best option to restore connectivity".

The Lancaster Wetlands are a haven for wildlife that gives shelter to more than 250 species of birds and 80 species of mammals, reptiles and amphibians. Many of these species are endangered, and the wetlands are home to a higher level of biodiversity than can be found in most small countries.

In order to build the dam, however, many tons of material were illegally extracted by the ICE from the base of the cliff which supports the Lancaster Wetlands, leaving it in very high risk of a landslide. The collapse of these wetlands due to this illegal extraction would be nothing short of an environmental disaster for Costa Rica.

ICE workers extracting material from the base of the cliff that supports the Lancaster Wetlands

WHAT ARE THE ICE DOING TO MITIGATE THE DAMAGE?

The ICE deny causing any environmental damage and are doing nothing to avert the potential disaster. The owners of the wetlands have subsequently initiated a reclamation process with the project's investors - the World Bank (WB), Inter-American Development Bank (IDB) and the European Investment Bank (EIB) - for the environmental crimes committed and for non-compliance to clearly pre-defined environmental safeguards.

Their three claims have passed the eligibility process and they are waiting for the banks to take restorative action. Watch this video to find out more about this important environmental issue.

JUSTIFICATION FOR THE DAM

The often quoted justification for the environmental destruction caused by the Reventazon Hydroelectric Project is that it will provide clean energy and assist Costa Rica in achieving its goal of becoming carbon neutral. But is it really clean energy?

It's common scientific knowledge that areas to be flooded by Hydroelectric dams, particularly in tropical regions, should be cleared of all vegetation beforehand in order to avoid the production of greenhouse gas emissions. The ICE, however, did not clear the valley of organic matter as is clearly evident by the treetops still emerging from the lake. The lake is consequently now emitting large quantities green house gases such as methane and carbon dioxide which are the principle drivers of climate change.

The greenhouse gas emissions are also being multiplied by the proliferation of an invasive species of Water Hyacinth. These plants are feeding from the contaminated waters of the Reventazon and the stagnated organic materials generated by the ICE's failure to clear the reservoir.

These unavoidable facts clearly undermine the false claim that the energy being produced is in any way clean or green.

The Reventazon Hydroelectric Project is being sold to us as an environmentally friendly, flagship "green" engineering project to be admired and replicated throughout Costa Rica.

The ICE has already begun the permit process for a new Hydroelectric Dam. The Proyecto Hidroélectrico Diquís will flood an area 17 times larger than the Reventazon Reservoir. 12,500 hectares of land would be inundated, 2000 hectares of which are primary forests and sacred lands to indigenous people.

If the ICE are allowed to greenwash the significant environmental damage done by the Reventazon Hydroelectric Project they may gain the momentum to go on and desecrate many more of Costa Rica's pristine river systems. It is therefore of great importance to the biodiversity of Costa Rica that the truth about the biologically destructive and environmentally unsound nature of the Reventazon Hydroelectric Project is clearly broadcast.

To learn more see CNN's Worldwide Report on the project, for which they consulted The Jaguar Project's Simon Macara.